Which supplement is unnecessary during isoniazid therapy?

• A. Liver enzymes
• B. Folic acid
• C. Vitamin B6
• D. Vitamin C

Answer: (B)

Isoniazid can cause a deficiency of pyridoxine (vitamin B6) because it interferes with its metabolism, leading to neuropathy if not addressed. To prevent this, vitamin B6 supplementation is routinely recommended for those at risk during isoniazid therapy. Folic acid, however, is not typically affected by isoniazid and there is no standard need to supplement folate unless there’s a preexisting deficiency or another specific indication. Monitoring liver enzymes is important because isoniazid can cause hepatotoxicity, but that is a laboratory check, not a supplement. Vitamin C doesn’t have a routine role in this treatment regimen. Therefore, folic acid supplementation is not routinely required.